Radio antenna insulator for airplanes



Sept. 21, 1937. R. 1.. M COY RADIO ANTENNA INSULATOR FOR AIRPLANES Filed Sept. 27, 1933 Mm H 311mm Z. /)Z6 6 0 y Patented Sept. 21, 1937 UNITED STATES PATENT OFFICE RADIO ANTENNA INSULATOR FOR AIRPLANES Maryland Application September 27, 1933, Serial No. 691,212

2 Claims.

The invention relates to strain insulators and has for its general or principal object the provision of a strain insulator particularly adapted and in fact primarily designed for use in support- 5 ing radio antenna on an airplane.

It is known, without mentioning, that it is a common practice to equip airplanes with antenna for radio transmission. It is obvious that such antennae must be supported in insulated relation to the aircraft. A natural and logical requirement is that an insulator employed for such a purpose must be of such shape or design as to offer the minimum wind resistance. It is equally apparent that the insulator must possess certain definite characteristics as to mechanical strength, size and other details but principally as to the leakage distance between the metallic elements with which the insulator is associated, it being necessary to provide a rather long leakage distance in order to handle, safely, the voltage necessary in radio transmission.

It is with the above facts in view that I have devised the present invention which has for its primary object the provision of an insulator of stream-line design to reduce wind resistance and provided with holes for the passage of the metallic elements in lieu of the usual longitudinally extending grooves at the periphery.

An important object of the invention is to provide a strain insulator for this or any analogous purpose which may be made of the minimum diameter permitted by the thickness of material necessary to provide adequate puncture strength and which may be made of any desired length, of course within reasonable limits, in accordance with the desired leakage distance between the metallic elements which are interlinked within the body of the insulator in a manner analogous to the usual variety of strain insulator for guy and other purposes.

An additional object is to provide an insulator possessing these advantageous characteristics and which will at the same time be extremely simple and inexpensive to make, easy to install, eflicient and durable in service, and a general improvement in the art.

To the attainment of the foregoing and other objects and advantages, the invention preferably consists in the details of construction and the arrangement and combination of parts to be hereinafter more fully described and claimed, and illustrated in the accompanying drawing in which:

Figure 1 is a side elevation of an insulator constructed in accordance with the invention,

Figure 2 is a longitudinal section therethrough, Figure 3 is a cross section taken on the line 3-3 of Figure 1,

Figure 4 is a cross section taken on the line 4-4 of Figure 1. 5 Referring more particularly to the drawing the insulator is designated as a whole by the numeral lo and is formed of one piece of dielectric material, preferably porcelain. The insulator is formed with a pair of transversely extending 10 openings II which are arranged at right angles to each other and which are provided for the reception of the metallic elements l2, here represented as wires, one of which may be one end of an antenna and the other of which may constil5 tute means for anchoring the same to any desired portion of any type of aircraft to be equipped with radio transmitting apparatus. In the ordinary construction of insulators of this variety which are commonly known as guy 20 strain, the insulating body is provided at its periphery with longitudinally extending grooves leading from the ends of transverse passages or openings. However, in contradistinction to established practice, it is a feature of my invention that the dielectric body is formed with longitudinally extending pairs of holes or passages l3 which extend into or from the end portions of the transverse openings II and it is clear that the metallic elements l2 have their bight portions located within the openings II and their arms or sides extending through the holes or passages Hi. The construction, which is shown most clearly in Figure 2, is such that there is a wall or partition l4 between the holes or passages [3, this 35 wall having a curved end portion l5 within each passage II, this curved end being engaged by the bight portion of one or the other of the metallic elements I2. The metallic elements are shown in situ in Figure 1.

As the device is intended principally for use on aircraft, it is manifest that it is highly desirable that wind resistance be reduced to the minimum. For this reason I have represented the insulator as of substantially torpedo shape, that 45 is to say of a stream-line design, the ends being tapered off and rounded as clearly indicated. However, the important feature in this respect is to have the trailing end of stream-line shape as it is possible to have the forward end blunt or even square without material disadvantage from a wind resistance viewpoint, though it is thought obvious that if both ends are alike there will be no possibility of error in installation, thereby creating an additional advantage.

The insulator is actually connected or mounted in the same manner as any other strain insulator, that is to say the antenna wire to be supported has one end extending through the holes or passages l3 while the other wire constituting the anchoring means has its end engaged through the other pair of holes or passages and engaged within the other transverse opening l i. In actual practice some slight degree of manipulation may be necessary in effecting threading of a wire through one passage i3 into the associated transverse opening it and then threading the end through the other passage it prior to securing of the free end. However, this is a mere matter of wire bending and can be easily taken care of.

The point or principal importance involved in this case is the substantial enclosing of the metallic members within the body of the insulator, that is to say: throughout the major portion of their length. The advantage of this is the obtaining of a long leakage distance such as is necessary in the handling of the high voltages necessary for radio transmission. Owing to the fact that the ends of the dielectric body are tapered off it is clear that the holes or passages it open out to the periphery at points spaced back a short distance from the ends, or in other words the holes or passages become grooves beyond the points 93 and from these points to the ends themetallic elements i2 are obviously exposed as indicated in Figure 1. The point is, however, that between the points it near the ends and the points H where the grooves or holes enter the transverse passages or openings l I there are wall portions 58 which entirely cover the metallic elements. The leakage distance is of course the same at both sides of the insulator and comprises the distance between the exposed bight portions of the metallic members plus the distances between the bight portions and the points of emergence of the wires l2 from the passages l3. In a properly designed insulator all three of these distances should be equal. It is thought clear from this construction and arrangement that the leakage distance may be made as great as desired by the simple expedient of providing a longer insulator, there being no necessity for increasing the diameter as is the only way to increase the leakage distance in strain insulators of the com mon or grooved type. Heretofore to obtain proper leakage distance it has been necessary to use a series of ordinary strain insulators, this adding naturally to the cost and to the amount of work involved in installation. By using an insulator constructed in accordance with my invention the leakage distance may be made anything desired without it being necessary to use more than one insulator. Moreover as but little puncture strength is necessary the diameter can be very small and this coupled with the stream-line shape will clearly reduce wind resistance to practically nothing.

From the foregoing description and a study of the drawing it will be apparent that I have thus provided a very simply constructed insulator which may be formed of porcelain or other appropriate dielectric material and which may be readily out while in a green or plastic condition in a manner well known in the insulator art without involving any undue time or labor. The device is bound to be inexpensive and will possess the various advantageous characteristics above pointed out. It is thought that the construction, operation and advantages should be clear to one skilled in the art without further explanation.

While I have shown and described the preferred embodiment of the invention, it should of course be understood that its use is not limited to supporting the antenna on a radio equipped aircraft as it may be easily capable of employment for a wide variety of purposes. In fact I reserve the right to make all such changes in the formation and specific details as will constitute n0 departure from the spirit of the invention or the scope of the claims hereunto appended.

Having thus described the invention, I claim:

1. A strain insulator comprising an elongated cylindrical body of dielectric material formed at longitudinally spaced points with right angularly disposed openings extending entirely therethrough, the body being further formed with pairs of longitudinally extending passages lying in planes at right angles to each other and extending toward the respective ends of the body, the ends of the body being tapered and curved to reduce wind resistance, and said passages being enclosed throughout the major portion of the body and emerging at the periphery at points spaced inwardly from the ends, the distance between said points of emergence and the points where said passages lead into the transverse openings and the distance between the openings defining separate leakage paths at each side of the insulator between metallic elements disposable within the transverse openings and through said passages, all of said paths being substantially equal and the paths at each side being in multiple.

2. A strain insulator comprising an elongated cylindrical body of dielectric material having tapered ends and provided at points spaced inwardly from its ends with angularly disposed transverse openings extending therethrough, the body being further provided with pairs of longitudinally extending passages, one pair extending from the opening at one end of the insulator toward the other end and the other pair extending from the opening at the other end of the insulator toward the one end, said pairs of passages at their ends emerging at the sides of the body at points between the ends of the body and the adjacent transverse openings, and each transverse opening being located substantially midway between the opposite ends of the adjacent pair of longitudinal passages whereby there are provided leakage paths of substantially equal length.

ROBERT L. MCCOY. 

